1. Field of the Invention
The present invention relates to spread spectrum radio communication systems, and more particularly, to a radio transceiver for wireless network communication between mobile and/or stationary computers.
2. Description of the Prior Art
Wireless computer communication, commonly referred to as "wireless networking", represents the merging of radio technology and networking technology. Wireless communication permits a mobile/stationary computer to transfer information, in accordance with a predefined networking protocol, to another mobile/stationary computer via a radio medium. The mobile wireless networking environment presents many technical challenges. Mobile computers are limited in size, power, and tend to be used in remote locations. Each of these factors greatly complicates the radio design of the mobile computer.
The standard radio transceiver includes a receiver and a transmitter. The transmitter is responsible for modulating a baseband signal onto a carrier frequency signal during transmission. Modulation is the modification of the high frequency carrier signal to include the relatively low frequency baseband signal. The receiver is responsible for retrieving the baseband signal, and hence recovering the transmitted information, from the carrier signal during reception. A single antenna is typically shared between the receiver and transmitter of the transceiver. A switch or circulator is used to, in effect, share the operation of the antenna between reception and transmission.
Standard transceiver design typically includes a separate transmitter and a separate receiver. The transmitter includes a first set of dedicated filters, mixers and amplifiers and the receiver includes a second set of dedicated filters, mixers and amplifiers. Filters, mixers, or amplifiers are typically not shared between the receiver and the transmitter.
The standard transceiver design has many disadvantages when used in the mobile computing environment. The component parts required to implement the separate receiver and the transmitter are numerous, cumbersome and difficult to lay out on a circuit board in a space efficient manner. As a result, the boards tend to be relatively large, heavy, consume a significant amount of the battery power, and are difficult to install into a mobile computer, where space, light weight, and battery power are at a premium. The large number of component parts required to implement the standard transceiver in a mobile computer is expensive, reduces reliability, and increases manufacturing complexity.